On the day President Obama was inaugurated for his first term, in January 2009, I was on patrol and driving the streets in South-Central Los Angeles. Driving a fully marked police car, I had stopped for a red light at a busy intersection, and when the light changed to green, I started to drive through. In the corner of my eye I spotted something, and I had to brake suddenly to avoid flattening a man running the red light on a bicycle. He was wearing a “President Obama” t-shirt, and as he passed within a foot or two of my front bumper — the bumper that might have killed him — he looked at me, smiled, raised a fist in the air, and shouted, “Obama!” In due course we were involved in a conversation, during which I advised him that President Obama said we still have to stop at the red lights.

As was the case in many cities across the country, in South-Central L.A. there was a palpable sense of optimism in the air when the president took office. Here was the man, people believed, who would make things better. Now, four and half years later, little has improved and much has gotten worse. According to the Los Angeles Times, since January 1, 2007, 574 people have been murdered within three miles of the intersection where I nearly ran over that jubilant cyclist, and the pace of this killing has been just as horrific since Mr. Obama’s taking office as it was before.

I was thinking about that bicyclist and the carnage in that neighborhood as I listened to the president’s Friday remarks on race. He spoke about black men being followed in department stores and hearing car doors lock as they pass and seeing women clutch their purses in elevators, all of it intended to arouse guilt in people so backward as to harbor irrational fears of their black fellow citizens. And though the president acknowledged that blacks are “disproportionately involved in the criminal justice system,” and claimed that he wasn’t making excuses for this, he went on to, yes, make excuses for it.

“[Blacks] understand,” he said, “that some of the violence that takes place in poor black neighborhoods around the country is born out of a very violent past in this country, and that the poverty and dysfunction that we see in those communities can be traced to a very difficult history.”

A “difficult history” is what’s being created this very day and every day that people blame the dead past for condemnable behavior. Crime among blacks is worse today than it was during the Jim Crow era, an inconvenient fact for the president’s hypothesis.

Blacks will no longer be followed in stores or hear car doors locking or see women clutching their purses in elevators when one can no longer look at a crime map of a city — like this one of Chicago — and identify the black neighborhoods by seeing how much more crime occurs in them. Until then, despite the president’s lectures, people will carry on much as they have.

— Jack Dunphy is an officer in the Los Angeles Police Department. “Jack Dunphy” is the author’s nom de cyber.